【摘要】 为了研究不同退化梯度高寒草甸土壤重金属污染状况,以祁连山东部天祝县高寒草甸土壤为研究对象,研究高寒草甸4种退化草地(未退化草地(ND)-轻度退化草地(LD)-中度退化草地(MD)-重度退化草地(HD))中土壤理化性质(全氮、全磷、全钾、全碳等)和6种重金属元素(Cu,Cd,Pb,Zn,Ni和Cr)含量的测定,结合甘肃土壤背景值和《国家土壤环境质量标准二级标准》为参比值,应用内尔梅罗综合指数法和潜在危害生态指数法对高寒草甸不同退化梯度土壤重金属污染进行污染评价。结果表明:研究区同一土层随着退化的加剧,土壤养分全氮、全磷、全钾和全碳含量呈下降趋势,同一退化梯度随着土层的加深,全磷、全钾、电导率和pH呈上升趋势。土壤重金属含量Cu,Pb,Zn,Ni,Cr平均值均大于甘肃土壤背景值,小于二级标椎,变异系数小于0.5,土壤重金属含量在同一土层随退化梯度的加剧,Cu、Zn、Ni元素呈下降趋势,Cd,Pb,Cr元素呈递增趋势,具富集趋势。土壤重金属含量与土壤养分之间相关性显著,重金属之间相关性显著,重金属来源相似。0—10 cm土层LD样地、10—20、20—30 cm土层ND样地的内梅罗综合指数小于2,为轻度污染,主要污染物Pb;0—10 cm土层ND样地、10—20、20—30 cm土层LD样地内梅罗指数均小于3,土为中度污染,主要污染物Pb、Cr。土壤中的6种重金属元素潜在危害生态系数(E_r~i)均<40,潜在生态危害指数(RI)均<150,属轻微生态危害,Cd元素最高E_r~i为12.54—18.65,Cu元素次之。研究地区重金属含量已具有富集趋势,应采取有效措施进行缓解和治理。该文为天祝县不同退化草地环境风险评价提供基础,旨在为草地退化恢复提供数据支持。更多还原

【Abstract】 to study the heavy metal pollution status in soil of alpine meadow with different degradation gradients,alpine meadow soil in Tianzhu County,east of Qilian Mountains was taken as the research object,the soil physicochemical properties (total nitrogen,total phosphorus,total potassium,total carbon and others) of 4 degraded grasslands (undegraded grassland (ND)-lightly degraded grassland(LD)-medium degraded grassland (MD)-heavily degraded grassland (HD)) were studied,and the contents of 6 heavy metal elements(Cu,Cd,Pb,Zn,Ni and Cr) were determined.By taking the soil background value of Gansu Province and national soil environment quality standard (level 2) as reference value,the Nemerow composite index method and potential ecological risk index (RI) method were used to evaluate the heavy metal pollution in soil of alpine meadow with different degradation gradients.The results showed that:the contents of total nitrogen,total phosphorus,total potassium and total carbon in the same soil layer decreased with the aggravation of soil degradation,while the contents of total phosphorus and total potassium,electrical conductivity and pH showed an upward trend with the deepening of soil layer in the same degradation gradient.The average content values of Cu,Pb,Zn,Ni,Cr in soil were higher than the soil background value of Gansu,which was less than that in national soil environment quality standard (level 2),and the coefficient of variation was less than 0.5.In the same soil layer,with the aggravation of degradation gradient,the contents of Cu,Zn and Ni decreased,while those of Cd,Pb and Cr increased gradually,showing an enrichment trend.There was a significant correlation between the content of heavy metals and soil nutrients,the correlation between heavy metals was significant,and the sources of heavy metals were similar.The Nemerow composite indexes of 0?10 cm soil layer in LD sample plot as well as 10?20 cm and 20?30 cm soil layer in ND sample plot were less than 2,which belonged to light pollution,with the main pollutant as Pb;the Nemerow composite indexes of 0?10 cm soil layer in ND sample plot as well as 10?20 cm and 20?30 cm soil layer in LD sample plot were less than 3,which belonged to medium pollution,with the main pollutants as Pb and Cr.The potential ecological risk coefficient (E_r~i) of 6 heavy metals in soil were all less than 40,and the potential ecological risk index (RI) were all less than 150,indicating that they were slight ecological hazards.The highestE_r~i of Cd was 12.54?18.65,followed by Cu.The content of heavy metals in the study area has shown a trend of enrichment,and effective measures should be taken to alleviate and control.This paper aims to provide the basis for environmental risk assessment of different degraded grasslands in Tianzhu County,so as to provide data support for grassland degradation restoration.更多还原